Study On Estrusous Induction Of 2-tooth Northeast Half-fuzz Ewe At Anoestrus Season

The Northeastern Half fuzz is seasonal estrus sheep. At the experiment, 48 2-toothanoestrous ewes are treated with progesterone-impregnated vaginal sponges, and injectedwith PMSG on sponge withdrawal. Then we got the combination project of time of spongeplaced in vagin and dose of PMSG, the time of insemination, the difference of both ovariessensitivity to reproductive hermone. On the other hand, according to the progesteroneconcentrations, can we judge the feasibility of inductation estrous project? RevoIving andorthogonal regression design of the second power of two factors was adopted to study therelationship of variable Y (progesterone in plasm) with independent variable Xl (time ofsponge placed in vagin) and X2(dose of PMSG). Y is the sum of progesterone concentrationsin plasm collected on the eleventh,sixteenth and twentith days of sponge withdrawal; Theupper limit of Xl is l4 day(366hour), and the lower limit is 6 day(144hour); The upper limitof X2 is 450IU and the Iower limit is 50IU. Blood samples were taken from juguIar vein eighttimes fOr determining the progesterone concentration in trial period. Ewes were inseminatedinto uterine 48 hours after the injection of PMSG or removal of sponges. After five months,lambing ewes were registered. The results were as fOllowed:1. According to the optimizatiom of Y model with Xl and X2 and the sum of progesteroneconcentrations in plasm of 22 lambing ewes, we can get the most problely pregnantedtime and dose are l74~245 hours and l45~254IU or 5~7IU/kg.2. If the estrous was tested by rams, the insemination was done in l2 hours of estrous onset.lf estrous ewes weren't found, the insemination' into uterine should be performed withsemen 48 hours after the removaI of sponges.3. In late anoestrus, there are medium follicles on the ovaries of Northeastern Half fuzz22-tooth ewes. And right ovary of this breed is more sensitive to reproductive hermone than the left one. So when we are not sure the developmental status of ovaries, semen should be inseminated into the right uterus.4. The feasibility of inductation estrous project can be judged by the progesterone concentrations in plasm on the eleventh.sixteenth and twentith days of sponge withdrawal.Postgraduate: Cong Huimin Supervisor: Prof. Li Wu Major: Animal reproduction...